1. Field of the Invention
The present invention relates generally to a finishing apparatus that can be used, for example, with an electrophotographic printing machine, and more particularly, to a unique structure for a sheet order gate for use in such a finisher that addresses the issue of reliable guiding the lead edge of sheets that are fed into a compiler past the trail edge of compiled sheets.
2. Brief Description of Related Developments
In the field of on-line finishing of copy sheets, many attempts have been made in the past to fill the need for a system that will compile copy sheets within an output tray of a finisher without damaging the copy sheets or causing set disturbance to a set of sheets in the process, e.g., by using angled paddle wheels or side tampers that offset sheet sets. However, experience has shown that these methods of handling copy sheets within a finishing apparatus have not been entirely satisfactory especially when the finisher is used with printing machines that produce copy sheet sets for finishing at very high rates of productivity. In typical prior art type sheet stacking apparatus, there is a tendency to allow sheets, as they are being compiled in a finishing apparatus, to stack in an incorrect order. When assembling any document in a specific order, this lack of organization, i.e. lack of the ability to stack sheets in the correct order, will present a very major disadvantage.
In accordance with the specific features of the present invention there is provided a sheet stacking apparatus that will overcome the disadvantages of prior art systems as explained above by having an inclined tray for receiving sheets for stacking, and a sheet order gate for first guiding lead edges of each of the sheets that are being fed to the stack and subsequently for guiding trail edges of each of the sheets to the stack of sheets to be positioned in the tray in their correct order, the apparatus comprising, a sheet order gate device having a plurality of control surfaces which form channels for moving the sheets therein, the control surfaces having a lowermost portion, each of the channels consisting of two control surfaces, the gate device adapted to rotate in segments, thereby rotating the control surfaces in segments, each segment adapted to position a lowermost control surface to force a trailing edges into the tray; and a sheet feeding device for feeding the sheets by their lead edges into the inclined tray such that the lead edges of each of the sheets rest on a backstop, and the trailing edges of each of the sheets are positioned at a level above the lowermost portions of the control surfaces.
In accordance with other embodiments of the present invention there is provided a process for feeding and stacking sheets in an inclined tray in a correct order comprising the steps of feeding each of a series of sheets through channels each channel formed of two control surfaces, the control surfaces forming a portion of a sheet order gate allowing a lead edge of each sheet to fall within the tray such that the lead edge rests on a backstop in the tray, the position of the backstop being arranged to permit a trailing edge of each sheet to fall above a lowermost portion of the control surfaces and of a set of control surfaces; and forcing the trailing edge of each sheet against the tray by rotating the sheet order gate through a segment and causing the lowermost portions of the control surfaces to push the trailing edges into the tray.